Apparatus for the recovery of values from aluminum



Jan. 26, 1937.

Filed Aug. 5, 1935 APPARATUS FOR THE RECOVERY OF VALUES FROM ALUMINUM 2Sheets-Sheet l 7ZINI 5- I2 I 1 Gavmme Sop/1M flu/m/mn: SOLUTION 3;

l /0 LEM/K Cg Z7 TfiI/CKEA EE 3 I 29 I z 40 NxOl-l 77'l/VK INWENTORSJan. 26, 1937.- A. F. BAUMBAUER El AL 2,068,640

APPARATUS FOR THE RECOVERY OF VALUES FROM ALUMINUM Filed Aug. 5, 1955 2Sheets-Sheet 2 I INVENTORS z W 3 BY M02 5 M ATTORNEYS Patented Jan. 26,1937 I 2,068,6tel

UNITED STATES PATENT OFFICE APPARATUS FOR THE RECOVERY OF VALUES FROMALUMINUM Allen F. Baumbauer and William Culver, Long Beach, Calif.; saidCulver assignor to said Baumbauer Application August 5, 1935, Serial No.34,776

7 Claims. (Cl. 23-267) This invention relates to an apparatus for andprovided with an iron grate in the lower portreating metallic aluminumin the form of scrap tion as indicated at 4, and another grate posiorthe like, and containing varying quantities of tioned in the upper thirdof the tank, as indipure aluminum, for the production of hydrogen catedat 5. The dome is provided with a gas gas, alumina (either in the formof hydrate or discharge line 6 whereas the cone bottom is pro- 5:

oxide), sodium aluminate, and the like. vided with a valved outlet 1.The feeder pref- Although it has been known for a great many erablycomprises a cylindrical portion H3 and a years that sodium hydroxidesolutions will react conical bottom II, the bottom being connected withmetallic aluminum with the formation of by means of a line l2 with thelower portion hydrogen and sodium aluminate, this well known of thegenerator 3 at a point immediately above 10 reaction has not beenutilized heretofore in the the lower grate 4. The conical portion ll ofthe recovery of values from scrap aluminum or metals er l iS providedWith a Spiral bafiie l3, the containing aluminum, for economical reasonsbafile being inclined downwardly and toward the and the lack ofequipment capable of handling center of the cone H. A port or apertureexthe reagents and products in a ready, facile and tends o g t e bafi l3a a hot aust c 1'5 economical manner. inlet line 2 dischargestangentially into the cone The present invention is directed toward an Hat a Point e t the hem Th y arrangement of elements and the provision ofdrical portion In y b p d With a series means whereby metals containingaluminum may of apertures l4 leading into manifold l5 p be economicallyutilized in the production of vidcd with a caustic return line 20valuable products. The invention also provides In operatlon, hot icsolution discharges means reagents and conditions whereby the 0p- Int-0the Cone beneath the bafile is, forming a eration is facilitat d quietwhirlpool which draws down with it pieces An object of this invention,therefore, is to disof metal cqntaining um num fed into the top,

5 close and provide an arrangement for treating the cyllndllcal DOItiOIIl0 d scharging the mixmetals containing aluminum for the production P-otaluminum metal nd caustic through the of hydrogen and alumina,therefrom line l2 into the gas generator 3 between the grates f Anotherobject of the invention is to disclose 4 and T grates 51551811 n reta nng the solid and provide means f economically utilizing the metal w1th1nthe generator, violent ebullition and reagents reaction taking placetherein. A plurality of 30 other objects, uses and advantages f thevertically spaced observation windows I! is provention will becomeapparent to those skilled in Vlded m the generator 3 t ove and below theart from the following detailed description. the grate so that thehelgl'lt ickness of In such description, reference will be had to thefoam Wlthm the generator may be ually obpp drawings in which: served. Asampling outlet [8 is provided in the 35 Fig 1 diagrammaticallyillustrates an arrange lower portion of the generator 3 at a point abovement of elements whereby the Operation may be the giate 4. Gasd1scharged through the outlet most economically carried out. g y the gash er tin is so arge as y me 1nto rylng and scrubgg 2 1S slde eleva'nonof t 8 gas gen g bing towers, Indicated at 22, from whence the ,40

Fig. 3 is an enlarged vertical section through Wished gas may bed1scharged by hne 23 Into the feeding device which forms a part of thesuitable storage tanks, compressors, etc. The gas ge g unit sodiumalummate solution, together with products of reaction taking place inthe generator 3, is

: AS shown m the drawmgs the apparatus com discharged by line 1 into adilution tank 24 which 45 prises a feeder I into which hot caustic sodais preferably of the dome top, cone bottom yp solution is tntroduced imeans the Water from the scrubbers 22 may be introduced Scrapaluminum-containing metal in relatively into the dilution tank 24 bymeans of a line 25 small pieces is also fed into the feeder I so thatand mp 25 The water inlet line 25 is preferboth the aluminum metal andcaustic soda are ably Spaced from t bottom of t tank 2 The 50 introducedinto a gas generator The valved outlet 21 leading from the bottom of thestruction of the gas genemtcr and feeder is tank 24 discharges into asettling tank 28 from more accurately shown in Figs. 2 and 3. whence thesupernatant, partially clarified liquor The g generator 3 y b acylindrical tank is withdrawn by lines 29 into one end of apluralprovided with a conical bottom and a domed top ity of thickeningtanks 30. Sediment may be 55 withdrawn from the tank 28 by a valvedbottom outlet 3I.

The thickeners 30 may be provided with slow moving rakes or paddles. Thethickened sludge may be discharged by lines 32 into a suitable filter33, the solids being conveyed and passed into a drier 34. The drier 34may be either heated by means of a jacket or may be of the direct firetype.

The substantially clear thickened solution discharged from thethickeners 30 by lines 40 is conveyed to a suitable concentrating unit,such as the evaporator M In the evaporator the relatively weak alkalinesolution is concentrated to about 30% NaOH or to a specific gravity ofapproximately 1.33. The hot concentrated caustic soda solution may bedischarged into a tank 42 by means of line 43 and supplied therefrom indesired quantities to the feeder I as by line 2.

In actual operation, a hot caustic soda solution containing about 30%NaOH is fed into the generator 3 through the feeding device I.Simultaneously therewith, pieces of metal containing aluminum are fedinto the hopper II] of the feeding device I. The feeding device I islocated at a height above the generator 3 sufiicient to maintain apressure of from 6 to 10 pounds in the dome of the generator. In theevent undue pressure develops in the dome, the caustic solution willback up into the cylinder II] of the feeder I and be discharged throughthe apertures I4 into the manifold I from whence the excess caustic ispermitted to run up line I6 into the caustic storage tank 42. Within thegenerator 3 a reaction takes place whereby sodium aluminate and hydrogenare formed. The reaction may be indicated as follows:

The hydrogen is discharged by the line 6 into the tank 20 and then intothe drier or scrubbing towers 22. The products of reaction, togetherwith the partially spent alkaline solution, are discharged by line 1into the dilution tank 2 In this tank the dilution causes the formationof caustic soda and aluminum hydrate as follows:

Although the formation of aluminum hydrate takes place in the tank 24,the material is maintained at a relatively elevated temperature thereinand in the settling tank 28. Only coarse solids such as iron, etc, aredischarged from the settling tank 28 by line 3I. The fluid suspension ofaluminum hydrate passes into the thickeners 30 wherein precipitationtakes place, the weak caustic solution being withdrawn through line 40whereas the aluminum hydrate passes out through the lines 32. The weakcaustic soda solution is then reconcentrated in the effects 4| andreturned to tank 42.

The aluminum hydrate passes into the filtering and washing units 33 andthen into the driers 34. In such driers it has been found desirable toadd a small quantity of calcium fluoride (say 1%) as otherwise thedehydrated or dried alumina A1203 dusts very excessively.

It will thus be seen that a compact, simple apparatus has been disclosedcapable of converting metallic aluminum into hydrogen and either sodiumaluminate, aluminum hydrate or aluminum oxide. In the operation of theprocess, the temperature of the caustic being supplied to the feeder Ishould be maintained above 220 F. for most economical operation. Thecaustic storage tank 42 may be dispensed with. The temperature in thedilution tank 24 as well as in the settling tanks and thickeners 28 and30 should preferably be maintained at above 150 F.

The feeder I as stated hereinabove, is designed to permit eithercontinuous or intermittent introduction of metallic aluminum into thegenerator without admission of air. The vortex means, such as the spiralbaflles I3, produce a quiet whirlpool which permits the introduction ofmetallic aluminum without drawing in air, the cylindrical body portionIll of the feeder being of sufiicient height so that the liquid leveltherein is at all times above the bafiles I3. It is to be understoodthat suitable pumps may be introduced at various points in the system asoccasion requires. Furthermore, instead of using a sedimentation tank at28, a continuous filter may be substituted therefor.

In conducting the process, it is desirable to maintain the molecularratio between NazO to A1203 at between 2.15 and 2.5. The extent ofdilution and the rate of thickening in the settlers and thickeners 30 iscontrolled so that the suspension in the thickeners 30 is reduced toabout 15 B., the dilute alkali solution discharged by line 40 being thenconcentrated to about 36 B. in the evaporators 5!.

All changes and modifications coming within the scope of the appendedclaims are embraced thereby.

We claim:

1. In an apparatus for the treatment of metallic aluminum, thecombination of: an enclosed generator provided with spaced horizontalgrids, a gas outlet from the top and a liquid outlet from the bottom;feeder means for introducing hot caustic and pieces of metallic aluminuminto the generator at a point adjacent the lower grid and between saidgrids; a dilution tank communicating with said liquid outlet from saidgenerator; settling and thickening means; conduit means connecting saiddilution tank with said settling and thickening means; means fordischarging aluminum hydrate from said thickening means; an evaporatingmeans; means for separately discharging caustic solution from saidthickening means into said evaporating means; and means for conductingcaustic from said evaporating means into said feeder means.

2. In an apparatus for the treatment of metallic aluminum, thecombination of an enclosed generator provided with spaced horizontalgrids, a gas outlet from the top and a liquid outlet from the bottom; afeeder means positioned above said generator and including atangentially directed hot caustic inlet conduit and an outletcommunicating with said generator at a point in the lower portionthereof but between said grids; a dilution tank communicating with theliquid outlet from said generator; settling and thickening meansoperably connected to said dilution tank; evaporating means; and conduitmeans for conveying dilute caustic from said thickening tanks to saidevaporating means and for supplying said feeder means with concentratedcaustic from said evaporating means.

3. In an apparatus of the character described, the combination of acylindrical enclosed generator provided with spaced horizontal grids, agas outlet from the top and a liquid outlet from the bottom; feedermeans positioned above said generator and a cylindrical body por.

tion adapted to receive pieces of metallic aluminum, and a conical lowerportion, conduit mean connecting the conical lower portion with saidgenerator at a point in the lower portion thereof but between saidgrids, means for tangentially introducing hot caustic solution into saidconical portion; overflow means near the top of said cylindrical bodyportion, and means for conveying caustic from said overflow means into ahot caustic supply.

4. In an apparatus of the character described, the combination of acylindrical enclosed generator provided with spaced horizontal grids, agas outlet from the top and a liquid outlet from the bottom; feedermeans positioned above said generator and including a cylindrical bodyportion adapted to receive pieces of metallic aluminum, and a conicallower portion, conduit means connecting the conical lower portion withsaid generator at a point in the lower portion thereof but between saidgrids, and means for tangentially introducing hot caustic solution intosaid conical portion,

5. In an apparatus for the treatment of metaliic aluminum, thecombination of: an enclosed generator provided with spaced horizontalgrids, a gas outlet from the top and a liquid outlet from the bottom;feeder means for introducing hot caustic and pieces of metallic aluminuminto the generator at a point adjacent the lower grid and between saidgrids; a dilution tank communicating with said liquid outlet from saidgenerator; settling and thickening means; conduit means connecting saiddilution tank with said settling and thickening means; and means fordischarging aluminum hydrate from said thickening means.

6. In an apparatus of the character described, the combination of: acylindrical enclosed generator provided with spaced horizontal grids, agas outlet from the top and a liquid outlet from the bottom thereof;feeder means positioned above said generator and including a cylindricalbody portion adapted to receive pieces of material containing aluminum,a conical lower portion, conduit means connecting the conical lowerportion with said generator at a point in the lower portion thereof butbetween said grids,

means for tangentially introducing hot caustic solution into saidconical portion; a dilution tank communicating with said liquid outletfrom said generator; settling and thickening means; conduit meansconnecting said dilution tank with said settling and thickening means;and means for discharging aluminum hydrate from said thickening means.

7. In an apparatus of the character described, the combination of acylindrical enclosed generator provided with spaced horizontal grids, agas outlet from the top and a liquid outlet from the bottom; feedermeans positioned above said generator and including a cylindrical bodyportion adapted to receive pieces of metallic aluminum, and a conicallower portion, conduit means connecting the conical lower portion withsaid generator at a point in the lower portion thereof but between saidgrids, means for tangentially introducing hot caustic solution into saidconical portion; a dilution tank communicating with said liquid outletfrom said generator; settling and thickening means; conduit meansconnecting said dilution tank with said settling and thickening means;means for discharging aluminum hydrate from said thickening means; anevaporating means; means for separately discharging caustic solutionfrom said thickening means into said evaporating means; and means forconducting caustic from said evaporating means into said tangentialintroducing means of said feeder.

ALLEN F. BAUMBAUER. WILLIAM CULVER.

